If you like playing video games, you might want to check out some text heavy old school RPGs, like Might and Magic, Baldurs Gate, Wizardry, Dark Sun, pretty much any DOS RPG made before 95' or so. I remember learning a lot of big words as a child from games like that.

English is not the new latin, the thounge of the learned, but the language of the warwinners of superior production.

Most European languages have lots of foreignwords from latin or french or loanwords from other languages, which makes them about as rich as latin itself, so there is not really a reason today to speak a foreign language when you can express yourself best in your own thounge.

English as the lingua franca of a dying modern world couldn't be any more culture deprived. It literally is the language of trolls and orcs. I would agree that it's better to be a master of your own tongue, and if you succeed all the geniuses will translate you anyway.

I'm quite partial to English though it is also not my first language, it has a kind of rolling charm to it (metred verse in English used to strike me as funny). While I think its great that you get recommendations for some fine works for improvement, the most important thing is quantity. Read a lot and write a bit.

I don't think there was anything better than Fantasy literature for me but since you're looking for function and not pleasure that may not be good advice for you. Find out what you like and read about it; keep a dictionary (online or otherwise) handy. Voila.